Replacing honeywell t6360B with DT92E

[Boffinboy]

Hi there, I am planning to replace my T6360B with a wireless DT92E. The thermostat currently sits on my garage wall, in the hall, and as such the temperature is very low, which means the boiler turns on and off far too frequently. My boiler is a condenser potterton promax HE boiler, situated in the kitchen, with a honeywell st6400c timer.

I'm slightly unsure how to wire up the new thermostat.

The T6360B is wired as follows:

earth connected
1 - red wire (live?)
2 - nothing
3 - yellow (switched live?)
4 - nothing
blue (neutral?) is free/terminated

I am guessing the DT92E should be as follows, but not sure

N - blue
L - red
2nd L to A link
B - yellow

Any advice would be much appreciated!

Ben

 

[D_Hailsham]

I am guessing the DT92E should be as follows, but not sure

N - blue
L - red
2nd L to A link
B - yellow

That won't work because the red wire will only be live when the ST6400C is telling the heating to turn on - the receiver requires a permanent live supply to L.

If you can't run a four wire cable to the current stat location (the green/yellow must NOT be used as a voltage carrying wire), the easiest solution is to locate the receiver near the wiring centre(W/C).

You then wire as follows:

Receiver - Wiring Centre
L ---------- Permanent live terminal (usually 1)
N --------- Neutral terminal (usually 2)
A --------- ST6400C CH ON terminal (usually 4)
B --------- Motorized valve terminal (white for mid position; CH valve brown for S Plan) (usually 5)

 

[Dan Robinson]

Why is the neutral not connected to terminal 2 of your existing stat?

 

[Boffinboy]

I am guessing the DT92E should be as follows, but not sure

N - blue
L - red
2nd L to A link
B - yellow

That won't work because the red wire will only be live when the ST6400C is telling the heating to turn on - the receiver requires a permanent live supply to L.

If you can't run a four wire cable to the current stat location (the green/yellow must NOT be used as a voltage carrying wire), the easiest solution is to locate the receiver near the wiring centre(W/C).

You then wire as follows:

Receiver - Wiring Centre
L ---------- Permanent live terminal (usually 1)
N --------- Neutral terminal (usually 2)
A --------- ST6400C CH ON terminal (usually 4)
B --------- Motorized valve terminal (white for mid position; CH valve brown for S Plan) (usually 5)

Thank you. Is it not OK for the receiver to only have a live when the timer is calling for heating? The rest of the time the receiver would not be needed so it wouldn't matter that the live was switched. I think if I'm not able to do a straight swap I'll probably have to get someone in to do it for me!

Thanks anyways

Ben

 

[Boffinboy]

Why is the neutral not connected to terminal 2 of your existing stat?

I am not sure, as I did not install it - looking at the manual for the t6360b it suggests the neutral is not used if between 6 and 10 amps

"For application between 6 Amps and 10 Amps, again use a T6360B,
but without the neutral connection (see above note regarding neutral
connection)."

 

[Dan Robinson]

How many amps are you putting through it?

For everyday installs, you need the neutral to stop the stat swinging on and off too quickly.

Get a CM901 and program a correction into it. Leave the timer on constant then transfer 1 & 3 to A & B.

 

[Boffinboy]

Again, I'm afraid I am not sure. From what you say, it sounds like it may be possible to connect the neutral (unless there is something unusual about my home setup which means the current is very high) which should help stop the frequent on and off?

I think perhaps I will need someone with some expertise to take a look, rather than doing myself!

How many amps are you putting through it?

For everyday installs, you need the neutral to stop the stat swinging on and off too quickly.

Get a CM901 and program a correction into it. Leave the timer on constant then transfer 1 & 3 to A & B.

 

[D_Hailsham]

Is it not OK for the receiver to only have a live when the timer is calling for heating? The rest of the time the receiver would not be needed so it wouldn't matter that the live was switched.

Although the receiver only springs into action when there is a call for heat, the controller sends regular signals to the receiver to check that it is working OK. If the receiver is not on all the time , the controller and receiver have to go through a communications check every time the receiver is turned on.